Studies on the Ovarian Development in Zebu Cattle (Bos indicus)

In a study of 71 female foetuses, gonadal blastema was observed at 1.5 cm crown rump length (CRL). Oogonial cells entered the meiotic prophase at 3.5-6.0 cm CRL, which was arrested at the dictyotene stage to produce primary oocytes which formed primordial follicles. Primordial follicles were observed at 6-8 cm CRL. All germinal cells were at dictyotene by 20-24 cm CRL and follicles developed to primary and secondary stages. Folliculogenesis dominated further ovarian development and reached a peak between 32 and 35 cm CRL. In seven of the 12 foetuses measuring between 41 and 72 cm CRL, many follicles were atretic and some luteinized. The luteal bodies were composed of hypertrophied theca and granulosa cells with homogeneous and eosinophilic cytoplasm.     

云南瘤牛

本文报道了云南瘤牛的产地,分布,习性和形态特征,并探讨了其起源与形成。云南瘤牛产于云南省中部,南部和西南部热带及地亚热带地区,性能耐热,耐湿,抗蜱;据出土文物和历史记载,云南瘤牛可能起源于云南,云南是中国瘤牛的重要起源地。     

Effects of Calf Removal at Parturition on Postpartum Ovarian Activity in Zebu (Bos indicus) Cows in the Humid Tropics

To assess endocrine and morphological responses of ovaries to total weaning at parturition, 6 Zebu (Bos indicus) cows 5 years or older were investigated. Following parturition, blood samples were collected daily during the first month and twice weekly thereafter until day 60 to determine concentrations of progesterone (P₄) and prostaglandin F_2α metabolite.It took between 25 to 32 days to complete uterine involution.The prostaglandin metabolite remained elevated for a mean period of 14.2 days (range, 4-21) postpartum. Five of the animals resumed cyclicity with a short estrous cycle starting between days 7 to 34 and lasting between 7 and 14 days. No estrous behavior was recorded prior to the short estrous cycles, but subsequent normal-length estrous cycles were all preceded by signs of estrus. In the 1 animal that resumed cyclicity with an estrous cycle of normal length on day 37 (length 20 days), the cycle was preceded by estrous behavior.Progesterone concentrations reached a mean maximum of 4.8 nmol liter⁻¹ during the short estrous cycles, and prostaglandin metabolite concentrations peaked while P₄ concentrations were decreasing. P₄ concentrations reached a mean maximum of 12.2 nmol liter⁻¹ during the estrous cycles of normal length. The interval from parturition to the first estrous cycle of normal length varied between 16 and 48 days, and the length of the cycle was 18 to 22 days.Starting 2 days postpartum, ovaries from 5 of the cows were scanned by ultrasonography every second day until day 30 postpartum. Medium-sized follicles were detected between days 4 to 7 postpartum in 4 of the scanned cows that later had short estrous cycles. The time between parturition and the appearance of the first dominant follicle was 7.6 days (range 6-10 days). The interval between parturition and the appearance of the first ovulatory-sized follicle was 10.2 days (range 8-13 days). In 3 of the scanned cows this ovulatory-sized follicle ovulated.We conclude that cyclic ovarian activity in Zebu cows can start early in the postpartum period in the absence of offspring, and that short luteal phases, not preceded by estrous behavior, may play an important role in establishing normal postpartum ovarian activity.     

固相RIA法测定血浆孕酮监测黄牛产后卵巢机能

应用１２５Ｉ固相放射免疫分析法，对２２头鲁西母黄牛产后期血浆孕酮（Ｐ４）的变化作了测定，以监测黄牛产后卵巢机能。结果表明，产后（１３．６±４．４）ｄ以前，母牛血浆Ｐ４浓度仍处于基础水平〔（０．３４±０．０４）～（０．５５±０．０６）μｇ／Ｌ〕，随后，Ｐ４开始升高，出现卵巢活动。代表卵巢活动的Ｐ４曲线可分为４种类型：Ⅰ型，产后（１０．６±３．９）ｄ后，曲线呈现３个正常的黄体周期；Ⅱ型，产后（１３．６±４．４）ｄ后，首先出现１个８．５ｄ左右的短黄体周期，接着出现２个正常的黄体周期；Ⅲ型，于产后（１２．５±３．９）ｄ后，先出现１个正常的黄体周期，继之出现１个短黄体周期和１个正常黄体期；Ⅳ型，产后（１２．５±２．５）ｄ后，出现不规则的黄体周期中，最低Ｐ４水平为（０．４５±０．１５）～（０．６０±０．３８）μｇ／Ｌ，最高浓度为（２．６５±１．９５）～（４．１７±２．３５）μｇ／Ｌ。试验表明，每隔４ｄ测定１次血浆Ｐ４浓度，可准确地判定母牛的发情周期     

Mother–Offspring Interactions in Zebu Cattle

The knowledge of the interaction between mother and offspring might contribute to enhance the welfare of the offspring and to improve the reproductive efficiency of the cow. However, there is still little information available about such interaction in some cattle breeds. A series of observational studies were set up, addressing the mother–offspring relationships of Nelore, Guzerat and Gyr cattle breeds. Firstly, the behaviour of cows and calves around the time of parturition was described, and then, the underlying factors that affect the calves' survival and development were studied. Special attention was given to the failure or delay in the first suckling. The results together are indicative of genetic variability for some studied variables, indicating the possibility of selection for calf vigour (using latency to stand up and latency to suckle as its indicators) and maternal ability (using percentage of time in contact with the calves), in spite of the estimates of heritability were low and presented high standard deviation for all variables. The individual variability in their suckling behaviour and the efficiency in first suckling cannot be explained by a single isolated underlying factor. By now, there are some results available, although there are many questions without answers. The field is still open for the development of future research.     

Incidence of Gross Reproductive Abnormalities in Small East African Zebu Cattle

Reproductive organs from mature Small East African zebu (SEAZ) heifers and cows slaughtered at the Morogoro abattoir were collected twice a month and evaluated over a period of 12 months. Out of the 402 animals from which reproductive organs were taken, 54% were pregnant, 24% were actively cycling and 22% were non-cycling. Various gross abnormalities were observed in the reproductive organs of about 16% of the cattle, and the major reproductive abnormality in both total and the non-cycling animals was various degrees of fibrous adhesion between the ovary and the infundibulum and mesosalpinx. It is concluded that, contrary to common belief, a majority of the female SEAZ cattle that are slaughtered are fertile.     

Postpartum Ovarian Activity and Serum Estradiol-17beta Level in Thai Crossbred Native Mares

To study the postpartum ovarian activities for investigation of first postpartum oestrus, twenty-five Thai crossbred native mares were monitored after parturition by oestrous detection, transrectal palpation and reproductive ultrasonography. Blood samplings were also taken for estradiol-17beta (E2) analysis. The first ovulation occurred within 20 days postpartum in 92% (23/25) of the mares. The mean intervals of foaling to first oestrus and to first ovulation were 10.3 +/- 2.9 and 13.4 +/- 2.6 days (mean +/- SD) respectively. Serum E2 increased from 7.0 +/- 2.9 to a peak of 10.8 +/- 3.3 pg/ml (mean +/- SD) at 2 days before ovulation. In conclusion, from the study, it can be stated that the postpartum breeding management should be considered after day 10 postpartum by careful examination of ovarian activity with various methods. However, the uterine condition should be also estimated associated with the ovarian activity after parturition which may increase breeding performance and foal production.     

影响奶牛产后卵巢周期活动恢复的因素研究分析

本研究通过对宁夏区内5个规模奶牛场的繁殖母牛生殖状况调查的基础之上,分析表明,产前体况评分为3.25～4,产后体况评分为2.75～3.5,年泌乳量为7 000～5 000kg,产犊季节在秋冬季、经产奶牛等因素与其相对应的对照组比较,产后卵巢开始活动的时间、产后第一次站立发情的时间、产后第一次配种时间明显提前（P〈0.05）,受胎率明显增高（P〈0.05）,产犊指数明显缩短（P〈0.05）。     

Ovarian Follicular Activity During Late Gestation and Postpartum in Guanaco (Lama guanicoe)

This study evaluated ovarian activity in late gestation and post‐partum in guanacos in captivity. Follicular dynamics was monitored every second day from 40 days before and other 40 after delivery by transrectal sonography and by plasma steroids concentrations. Seven out of eight (87.5%) of gestating females presented ovarian follicular activity under progesterone levels >3 nmol/l with maximum follicular size of 8.42 ± 0.83 mm from days 23 to 1 before delivery. After delivery, all females have follicular wave development from day 0 to 38, with larger follicular size and longer follicular wave phases and interwave interval when compared with pre‐partum data. During post‐partum period, there was a close relationship between follicle size and estradiol‐17β concentration, with r = 0.69 at the beginning of growth phase and r = 0.86 in association with the largest dominant follicle. Plasma estradiol‐17β concentration varied from 11.92 to 198.55 pmol/l. Plasma estrone sulfate, free estrone and progesterone returned to baseline concentrations during peripartal period and remained basal thereafter. The results described follicular activity during late gestation and early post‐partum period. These findings provide relevant information to understand physiological changes occurring during this reproductive key period in seasonal breeders with long gestation duration as New and Old World camelids.     

The Effect of Energy Balance on Ovarian Activity in a Herd of Norwegian Cattle

The study involved 34 primiparous cows fed ad libitum grass silage and fixed amounts of concentrate per cow and stage of lactation. It revealed that number of days from calving to maximum progesterone concentration in first luteal phase was negatively related to (p<0.05) energy balance summarized over weeks 3-12 post-partum. One standard deviation improvement of the summarized energy balance relative to the mean reduced the length of the anovulatory period by 12 days. Similarly, an improved energy balance enhanced progesterone secretion during the oestrus cycle and early pregnancy, as measured by 3 variables; 1) maximum progesterone concentration in first luteal phase, 2) cumulative progesterone secretion bounded by the maximum concentrations in first and in third luteal phase and 3) cumulative progesterone secretion in the first month of pregnancy. All results were supported by the estimated regression coefficients of the 4 ovarian activity variables on summarized non-estrified fatty acids and ac-etoacetate variables.     

Influence of Puerperal Uterine Infection on Uterine Involution and Postpartum Ovarian Activity in Dairy Cows

This article presents the results of a clinical trial designed to study the effect of puerperal uterine infection on uterine involution and on ovarian activity in dairy cows, monitored twice weekly from parturition until the sixth week postpartum (wpp). Infection significantly retarded uterine involution assessed by the uterine body diameter and a score of intrauterine fluid volume (IUFV). By the sixth wpp, cows with normal puerperium (controls) and cows that showed mild puerperal endometritis had similar uterine body diameter and IUFV, indicating spontaneous recovery within the postpartum voluntary waiting period. However, in cows with severe puerperal endometritis, although uterine body diameter had regressed to pregravid size, IUFV remained significantly higher than in control and mild endometritis cows, indicating that chronic endometritis was established. The IUFV score was positively and significantly correlated with uterine swab bacterial growth density and allowed diagnosis of endometritis after the third wpp. Cows with mild or severe endometritis had a significantly higher prevalence and persistence of pathogenic bacteria ( Escherichia coli , Actinomyces pyogenes , Gram-negative anaerobes – GNA) than controls. Actinomyces pyogenes was associated to GNA in 74% of isolations. Ovarian activity measured by ultrasound scanning of the ovaries and plasma progesterone (P4) concentrations was more abnormal (prolonged anoestrus, prolonged luteal phases and ovarian cysts) in cows with severe endometritis than in controls.     

An Update on Cystic Ovarian Degeneration in Cattle

Cystic ovarian degeneration (COD) is considered to be one of the most important causes of reproductive failure in cattle. There is a severe economic loss to dairy industry because COD increases days‐open in the postpartum period and the culling rates. The disease process is a consequence of a mature follicle that fails to ovulate at the appointed time of ovulation in the oestrous cycle. This anovulatory follicular structure either regresses or persists as a follicular or luteal cyst depending upon its structural/functional characteristics. The cells lining the follicular cyst synthesize oestrogen that, in certain instances, forces the animal to exhibit clinical signs of nymphomania. Besides oestrogen production, as per recent findings, they are also capable of secreting varying amount of progesterone which may dictate their fate. The animals that carry a luteal cyst may tend to be in anoestrus as the higher amount of progesterone secreted by this luteinized structure may change the pattern of gonadotrophins’ secretion. Present findings suggest that perturbation of the hypothalamo‐hypophyseal‐ovarian (HHO) axis, due to many exogenous and endogenous factors, as the cause for anovulation. For example, it has been suggested that lack of hypothalamic or hypophyseal response to the positive feedback effect of oestrogens that are secreted by the dominant follicle as one of the many causes. The non‐physiological changes that occur in the receptor expression of the HHO axis for the hormones involved in maturation, deviation, dominance and ovulation of the follicle may be yet another cause. The changes that occur at the cellular and molecular level in the ovary (in response to the factors mentioned above) that contribute to anovulation remain to be documented. This approach would allow us to completely understand the disease process. Hitherto, hormonal preparations that release luteinizing hormone from the anterior pituitary or have luteinizing hormone‐like action are used to treat follicular cysts. GnRH belongs to the former group and human chorionic gonadotrophin (hCG) hormone forms the latter group. Treatment with a luteolytic agent, prostaglandin F_2α (PGF_2α), is successful if a luteal cyst is diagnosed properly. Many agents may be developed in the future if the cellular and molecular pathways of the disease process are delineated. This article will review recent advances in our understanding of the pathogenesis of COD and suggest direction for future studies to completely understand the disease mechanism. This review will also discuss the existing method of treatments for cysts and methods proposed for treatment of cysts that tend to be refractory in nature.     

牛产后败血症及脓毒血症防治

牛产后败血症以全身症状表现为主,体温高热稽留,死亡率较高;脓毒血症以组织器官化脓为主要特征表现。预防该病需做好母牛疾病防控及产后护理,科学助产;抗生素是治疗该病的最佳药物,治疗该病建议采用局部和全身相结合的方案进行用药,同时,为加速疾病康复还应配合保健用药。     

Pregnancy Rate in Zebu Cows with Two Different Postpartum Intervals Exposed to a Two-Bull Rotational System

In order to evaluate the reproductive effect of a rotational breeding system, the pregnancy rate of 69 Zebu cows was assessed, 32 late postpartum (211±93 days postpartum, LP) and 37 early postpartum (averaging 63±8 days after calving, EP). In the LP group, 60% (19/32) were cycling before exposure to the bulls but only 38% (14/37) in the EP group. The two groups were dissimilar from the start (p<0.05). The cows were exposed in a rotational breeding system, with six Brahman bulls with previous sexual experience paired off in three groups (A–B, C–D and E–F). The cows were exposed to each pair of bulls for a period of 3 weeks, with one week in between each period, when the females were without the presence of a male. In the LP group, the pair of bulls A–B obtained a pregnancy rate of 72% (23/32), whereas for bulls C–D the pregnancy rate was 33% (3/9) and for bulls E–F the pregnancy rate was 67% (4/6). In contrast, for the EP cows, bulls A–B obtained a pregnancy rate of 32% (12/37), bulls C–D a pregnancy rate of 67% (12/18) and for bulls E–F a pregnancy rate of 55% (6/11). The percentage pregnancy obtained using the pair of bulls A–B differed (p<0.05) between LP and EP, whereas for bulls C–D and E–F it was similar. The pregnancy rate was different (p<0.05) in the first 3 weeks of mating for the LP group, the highest number of cows becoming pregnant during the first 3 weeks of the study. In contrast, the highest number of pregnancies in EP occurred evenly during the last 6 weeks. This study suggests that the reproductive performance of pairs of bulls in a 9-week rotational programme with the overall pregnancy rate is similar (94% in the LP and 81% in the EP). However, the time taken for the females to become pregnant, and hence the performance of the bulls, is related to the average number of days postpartum for the cows.